A water pump for the cooling system of a combustion engine of a car, of one type, si equipped with a housing with a space for fluid which contains a pump device placed on a shaft which projects outside of the housing. The rotates while being supported by a bearing assembly with a stationary outer ring mounted on the housing. The fluid space is sealed in relation to the shaft by means of a sealing unit equipped with a first ring connected to the shaft. A stationary second ring mounted on the outer ring of the bearing assembly. The rings are equipped with sealing surfaces which face one another or are about axial, and which are adjacent and sealed in relation to one another, whereby the first ring is loaded by a spring device in the direction of the second ring.